ALTERNATE SPLICING OF MOUSE FUSIN CXC CHEMOKINE RECEPTOR-4 - STROMAL CELL-DERIVED FACTOR-1-ALPHA IS A LIGAND FOR BOTH CXC CHEMOKINE RECEPTOR-4 ISOFORMS

Inspection of the intron splice junction of the mouse chemokine recept or fusin/CXC chemokine receptor R-4 (CXCR-4) revealed a potential in-f rame alternative splice site in the region encoding the N-terminal ect odomain of the receptor. Both predicted splice products were detected by reverse transcriptase-PCR. Cell lines of T lymphocyte, B lymphocyte , and macrophage lineage, plus populations of elicited peritoneal exud ate cells, thymocytes, and astrocytes coexpressed mRNA for both isofor ms. The full length cDNA of the shorter alternate splice product, term ed CXCR-4B, was cloned from peritoneal exudate cell RNA. Chinese hamst er ovary cells transfected with either isoform, CXCR-4A or CXCR-4B, re sponded to stromal cell-derived factor-1 alpha with a rise in intracel lular calcium. Both alternate splice products are therefore functional stromal cell-derived factor-1 alpha receptors.